Display device

ABSTRACT

A display device includes an element substrate including a display area where a plurality of self-light-emitting elements are formed, and a driver IC disposed outside the display area in the element substrate. A first metal layer is disposed on the reverse side of the element substrate at a position opposite to the display area. A second metal layer is disposed with a space between the first metal layer and the second metal layer on the reverse side of the element substrate at a position opposite to the driver IC.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese applicationJP2014-188588 filed on Sep. 17, 2014, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device.

2. Description of the Related Art

As one of display devices including a self-light-emitting element in apixel circuit, an organic EL display device is known.

In each of pixels of such an organic EL display device, aself-light-emitting element configured to include an upper electrode, alower electrode, and an organic layer interposed therebetween isdisposed. In the organic layer, holes and electrons injected from theupper electrode and the lower electrode, respectively, are recombinedtogether, so that light is emitted.

JP2010-114429A discloses an organic EL display device in which a heatequalizing means is provided on both the front and reverse surfaces of asubstrate.

SUMMARY OF THE INVENTION

When the self-light-emitting element described above is maintained at ahigh temperature for a long time, the life of the self-light-emittingelement is shortened.

Here, outside a display area where a plurality of self-light-emittingelements are arranged, a driver IC that performs display control of eachpixel in the display area is disposed. The driver IC is a heat sourceduring image display. Therefore, the self-light-emitting elementsarranged at a place near the driver IC are likely to be exposed to ahigh-temperature state, so that the deterioration of self-light-emittingelements may progress at the place.

In view of the problem described above, it is an object of the inventionto provide a display device in which the progress of deterioration of aself-light-emitting element in a display area due to a high temperatureis prevented.

(1) In view of the problem described above, a display device accordingto an aspect of the invention includes: an element substrate including adisplay area where a plurality of self-light-emitting elements areformed; and a driver IC disposed outside the display area in the elementsubstrate, wherein a first metal layer is disposed on the reverse sideof a position serving as the display area in the element substrate, anda second metal layer is disposed with a space between the first metallayer and the second metal layer on the reverse side of a position wherethe driver IC is disposed in the element substrate.

(2) In (1), the first metal layer and the second metal layer may becovered with a protective layer formed of an insulating layer.

(3) In (1) and (2), the driver IC may be disposed in an area exposedfrom a counter substrate that is disposed to face the element substrate,and the second metal layer may be bent while extending on the reverseside of the exposed area where the driver IC is disposed, and extend onthe reverse side of an area overlapping the counter substrate andlocated outside the display area where the plurality ofself-light-emitting elements are formed.

(4) In (1) to (3), the first metal layer and the second metal layer maybe divided by the space and each may be formed in an island-shape.

(5) In (1) to (3), the first metal layer and the second metal layer maybe electrically connected by means of a bridge portion composed of ametal layer, and the first metal layer and the second metal layer may bemaintained at the same potential.

(6) In (1) to (5), the first metal layer and the second metal layer maybe metal layers stacked in the same process by sputtering or vapordeposition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically showing an organic EL display deviceaccording to a first embodiment.

FIG. 2 is a plan view schematically showing the state of a reversesurface of the organic EL display device in the first embodiment.

FIG. 3 shows the state of a cross section at a predetermined position inthe organic EL display device in the first embodiment.

FIG. 4 shows the state of a reverse surface of an organic EL displaydevice in a second embodiment.

FIG. 5 shows the state of a reverse surface of an organic EL displaydevice in a third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, organic EL display devices according to embodiments of theinvention will be described with reference to the drawings.

First Embodiment

FIG. 1 is a schematic plan view for explaining an organic EL displaydevice 1 of a first embodiment. The organic EL display device 1 of theembodiment is configured by bonding a counter substrate B2 to an elementsubstrate B1 in which a plurality of organic electroluminescent elementsare disposed. In an area (exposed area EX) exposed from the countersubstrate B2 in the element substrate B1, a driver IC 2 for driving theorganic EL display device 1 is disposed.

In a display area DP of the organic EL display device 1, a plurality ofpixels as objects of display control are arranged in a matrix. In eachof the pixels, the organic electroluminescent element(self-light-emitting element) is disposed. As shown in FIG. 1, a firstscanning line BG, a second scanning line SG, a reset wire Vrst, and avideo signal line Data are connected to each of the pixels of thedisplay area DP. The first scanning line BG, the second scanning lineSG, and the reset wire Vrst are laid so as to be parallel to anX-direction, and the video signal line Data is laid so as to be parallelto a Y-direction. Although omitted in FIG. 1, a plurality of powersupply lines that supply the self-light-emitting elements with power arelaid so as to be parallel to the Y-direction.

The driver IC 2 in the embodiment is configured to include a signal linedriver circuit for outputting a video signal to each of the video signallines Data and a scanning line driver circuit for outputting varioussignals to the first scanning line BG, the second scanning line SG, andthe reset wire Vrst. Wires are routed from the driver IC 2 through apicture-frame area FR located around the periphery of the display areaDP, to thereby supply the first scanning line BG and the like with thesignals. The scanning line driver circuit or the video signal linedriver circuit included in the driver IC 2 may be configured as aperipheral circuit in the picture-frame area FR.

The driver IC 2 is connected with, via bumps and an anisotropicconductive film, a plurality of terminals formed in the exposed area ofthe organic EL display device 1. Hence, the heat of the driver IC 2generated by the driving of the organic EL display device 1 istransmitted to the plurality of terminals formed on the elementsubstrate B1 and to the surroundings of the terminals.

Here, especially FIG. 2 schematically shows the state of a reversesurface of the organic EL display device 1 of the embodiment. As shownin the drawing, a first metal layer M1 is disposed in a positioncorresponding to the reverse surface of the display area DP, and asecond metal layer M2 is disposed in a position corresponding to thereverse surface of the attached place of the driver IC 2. That is, thefirst metal layer M1 and the second metal layer M2 are disposed on asurface of the element substrate B1, which is composed of a glasssubstrate or the like, opposite to a self-light-emitting element-formingsurface.

In the embodiment, the first metal layer M1 is disposed so as toentirely overlap the display area DP and further overlap thepicture-frame area FR located around the periphery of the display areaDP, whereby dissipation, dispersion, and equalization of heat generatedin the display area DP are facilitated. Similarly, the second metallayer M2 is disposed so as to extend longer than the driver IC 2 whileoverlapping the entire driver IC 2 (disposed so as to extend longer thanthe length of the driver IC 2 in the longitudinal direction thereof),whereby the reverse surface of the exposed area EX is effectivelyutilized and thus the heat is dissipated and equalized in an area widerthan the area of the driver IC 2.

Further, a space is present between the first metal layer M1 and thesecond metal layer M2, and the space substantially corresponds to aposition on the reverse surface of the boundary between the countersubstrate B2 and the exposed area EX. Since the space is present betweenthe first metal layer M1 and the second metal layer M2, transmission ofheat from the central place of the driver IC 2 in which heat generationis large to the display area DP is prevented, so that the influence onthe life of the self-light-emitting elements in the central place (in adashed-dotted line frame R) of the edge portion of the display area DPon the driver IC 2 side and in the vicinity of the central place issuppressed.

FIG. 3 shows a cross-sectional view of the organic EL display device 1of the embodiment. The first metal layer M1 and the second metal layerM2 of the embodiment are formed by stacking, for example, metal having ahigh heat conductivity such as Al or Cu by a method such as vapordeposition or sputtering using a rough mask. Moreover, as shown in thedrawing, the first metal layer M1 and the second metal layer M2 arecovered with a protective layer PA composed of an organic insulatingfilm such as acrylic resin (the protective layer PA is not shown in FIG.2). Since the first metal layer M1 and the second metal layer M2 arecovered with the protective layer PA, the peeling-off or breakage of thefirst metal layer M1 and the like is prevented in the later process, andfurther, it is possible to reduce an adverse effect in the later processdue to the generation of foreign substances caused by the peeling-off orthe like. Moreover, it is also possible to prevent the corrosion of thefirst metal layer M1 and the like.

Second Embodiment

Next, a second embodiment of the invention will be described. FIG. 4schematically shows the state of a reverse surface of an organic ELdisplay device 1 of the second embodiment.

As shown in the drawing, in the organic EL display device 1 of thesecond embodiment, a second metal layer M2 is bent, and extends linearlyon the reverse surface of a picture-frame area FR. The picture-framearea FR in the embodiment is an area overlapping a counter substrate B2and surrounding the periphery of a display area DP. The second metallayer M2 extends linearly, on the reverse surface of an elementsubstrate B1, so as to be along the periphery of an area overlapping thedisplay area DP.

In this manner, since the second metal layer M2 extends from the reversesurface of the exposed area EX to the place overlapping the countersubstrate B2, the area of a heat conductive material is widely secured(the heat capacity of the heat conductive material is increased), andthus the equalization of heat generated from the driver IC 2 is furtherfacilitated. Moreover, since a portion of the second metal layer M2extending to overlap the counter substrate B2 is also disposed with aspace between the portion of the second metal layer M2 and the firstmetal layer M1, the heat generated in the driver IC 2 is prevented fromtransmitting to the display area DP (the reverse surface thereof).

The organic EL display device 1 of the second embodiment differs fromthe organic EL display device 1 of the first embodiment in the pointsdescribed above, but is configured substantially similarly to theorganic EL display device 1 of the first embodiment except for thepoints. Therefore, the description is appropriately omitted.

In the organic EL display device 1 of the second embodiment, the secondmetal layer M2 is configured so as to extend at two places on thereverse side of the picture-frame area FR. However, the second metallayer M2 may be configured so as to extend at one place on the reverseside of the picture-frame area FR. Moreover, the second metal layer M2is configured so as to extend, starting from an edge portion of thepicture-frame area FR on the exposed area EX side toward an edge portionon the other side, along the display area DP.

Third Embodiment

Next, a third embodiment of the invention will be described. FIG. 5schematically shows the state of a reverse surface of an organic ELdisplay device 1 of the third embodiment. In the first embodiment andthe second embodiment, the two metal layers, the first metal layer M1and the second metal layer M2, are formed in an island-like pattern inwhich the two metal layers are independent of each other and notcontinuous with each other, and thus separated from each other; whereas,the organic EL display device 1 of the third embodiment differs from thefirst embodiment and the second embodiment in that two metal layers areconnected by means of a bridge portion BR.

As shown in the drawing, in the organic EL display device 1 of the thirdembodiment, a second metal layer M2 and a first metal layer M1 areconnected via the bridge portion BR, whereby the two metal layers are atthe same potential to function as an electrostatic barrier of an elementsubstrate B1. The bridge portion BR in the embodiment is composed ofmetal of the same kind as the first metal layer M1 and the like. Thefirst metal layer M1 and the like may be connected, via a contact hole,with a wiring layer that provides a predetermined potential, and thewiring layer may be provided with a predetermined potential from aflexible printed board connected in the exposed area EX where the driverIC 2 is disposed.

Moreover, when the bridge portion BR is set as in the embodiment, acontact point between the bridge portion BR and the second metal layerM2 is desirably disposed so as to be separated as far as possible fromthe driver IC 2. As shown in FIG. 5, the longitudinal direction of theexposed area EX and the longitudinal direction of the driver IC 2 aredisposed so as to be substantially parallel to each other; it is betterfor the bridge portion BR to be formed avoiding an area between twolongitudinal-direction ends E1 and E2 of the driver IC 2 having arectangular-shaped structure; and a space between the first metal layerM1 and the second metal layer M2 is desirably secured in the areabetween the longitudinal-direction ends E1 and E2. Moreover, the bridgeportion BR may connect a portion of the second metal layer M2 extendingin the picture-frame area FR with the first metal layer M1.

Although, in the embodiments, the protective layer PA composed of theorganic insulating film and covering the first metal layer M1 and thesecond metal layer M2 is formed, the invention is not limited to such aform. The protective layer PA may be formed of an inorganic insulatingfilm (such as SiN_(x)), or the protective layer PA may not be formed.

Although the first metal layer M1 and the second metal layer M2 aredesirably formed simultaneously in the same process by a method such asvapor deposition or sputtering as in the embodiments, the invention isnot limited to such a form. For example, the first metal layer M1 andthe second metal layer M2 may be formed individually by attaching ametal thin film with an adhesive.

Although the display device in each of the embodiments is the organic ELdisplay device 1, the invention is not limited to this. For example, thedisplay device may be a display device including a self-light-emittingelement such as a quantum-dot light emitting diode (QLED) in each of thepixels of the display area DP.

The invention is not limited to the embodiments described above, butvarious modifications can be made. Various altered and modified exampleswithin the range of the idea of the invention will occur to thoseskilled in the art, and it is understood that the altered and modifiedexamples also belong to the scope of the invention. For example, whenthose skilled in the art appropriately add or remove a component orchange the design of a component in the embodiments described above, oradd or omit a process or change the conditions of a process in theembodiments described above, those are included in the scope of theinvention as long as they include the gist of the invention.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaims cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A display device comprising: a plurality ofself-light-emitting elements; an element substrate having a display areawhere the plurality of self-light-emitting elements are provided; adriver IC disposed outside the display area of the element substrate; afirst metal layer disposed on a reverse side of the element substrate ata position opposite to the display area; and a second metal layerdisposed on the reverse side of the element substrate at a positionopposite to the driver IC, and leaving a space from the first metallayer.
 2. The display device according to claim 1, further comprising aprotective layer which is formed of an insulating layer, and whichcovers the first metal layer and the second metal layer.
 3. The displaydevice according to claim 1, further comprising a counter substrate thatis disposed to face the element substrate, the element substrate havinga first area exposed from the counter substrate, the driver IC disposedin the first area, the element substrate having a second area which isoverlapped with the counter substrate, and which is arranged outside thedisplay area where the plurality of self-light-emitting elements areprovided, the second metal layer which is disposed on the reverse sideat a first position opposite to the first area, and which meanders fromthe first position to a second position opposite to the second area. 4.The display device according to claim 1, wherein the first metal layerand the second metal layer, which the space therebetween separate, eachstand insular.
 5. The display device according to claim 1, furthercomprising a bridge portion, which is a metal layer, and electricallyconnects the first metal layer and the second metal layer at an equalpotential.
 6. The display device according to claim 1, wherein the firstmetal layer and the second metal layer are of an identical metal layerwhich is deposited by sputtering or vapor deposition.